What is Vitamin D?
As nutrients go, Vitamin D is in a class by itself. That's because vitamin D is actually a hormone that the body produces in response to direct exposure of skin to direct Ultraviolet B (UVB) rays from the sun. Vitamin D is classified as a fat-soluble vitamin, which means that vitamin D you make and what you consume from foods and dietary supplements is stored in fat tissue for later use.
Benefits of Vitamin D
Vitamin D enhances your body's absorption of calcium from foods and supplements; it also regulates calcium's movement into, and out of, bones in order to maintain calcium levels in serum in the body. Without enough vitamin D circulating in your blood stream, absorption of adequate calcium is difficult.
That's not all Vitamin D does. Recent science suggests that Vitamin D influences cell growth, immune function, and may help support nervous system functions.
Adequate vitamin D is central to a strong skeleton.
How Much Vitamin D Do You Need?
According to the Institute of Medicine (IOM), the amount of vitamin D recommended daily depends on your age. From age one to 70, get 600 IU daily; people over the age of 70 should get 800 IU of vitamin D each day. Vitamin D requirements do not increase during pregnancy and breastfeeding.
Where Do I Get Vitamin D?
You can get Vitamin D from the sun, limited foods, and supplements.
Strong sunlight triggers vitamin D production in your skin. Your liver, kidneys, and cells throughout the body complete the conversion to vitamin D's most active form, 1,25-vitamin D3.
In theory, you should be able to make all the Vitamin D you need by getting adequate sunlight. In reality, many people do not produce the required vitamin D, and many fail to get what they need from food and dietary supplements. According to the 2010 Dietary Guidelines for Americans, most children and adults consistently come up short for vitamin D.
Several factors affect your vitamin D status. You may not have enough vitamin D in your body if:
Food Sources of Vitamin D
For such an important nutrient, few foods are natural sources of vitamin D. Some commonly-consumed foods, including milk and orange juice, are fortified with vitamin D. Most brands of yogurt and cheese do not contain added vitamin D, however. Here's a list of foods with vitamin D.
|Food||IUs per serving|
|Source: Adapted from Dietary Supplement Fact Sheet: Vitamin D.|
|Salmon (sockeye), cooked, 3 ounces||447|
|Mackerel, cooked, 3 ounces||388|
|Tuna, canned in water, drained, 3 ounces||154|
|Milk, any fat level, vitamin D-fortified, 1 cup||115-124|
|Orange juice, vitamin D-fortified (check labels for exact amounts)||100|
|Yougurt, fortified, 6 ounces||80|
|Egg yolk, 1 large||41|
Since relatively few commonly-consumed foods supply vitamin D, it's often difficult to get the vitamin D you need from the diet alone. For example, if you’re between the ages of one to 70, you’d need six eight-ounce glasses of fortified milk or orange juice; about 12 ounces of canned tuna; or a combination of three ounces of mackeral and nearly 18 ounces of fortified yogurt to meet your recommended daily vitamin D intake level. Dietary supplements can fill in gaps in vitamin D consumption, helping you to reach your daily goals.
In addition to inadequate vitamin D in the diet, people who are at particular risk for inadequate vitamin D levels in their blood stream because they avoid direct sunlight, or stay inside, may need a dietary supplement to satisfy their vitamin D requirements. The elderly and overweight may need more vitamin D than the recommended amounts for other adults. Some Experts in the field of vitamin D research believe that higher amounts of vitamin D than those recommended by the Institute of Medicine may be necessary for maintaining higher levels of vitamin D in the blood stream to support bone and general health. To find out how much Vitamin D is right for you, see your doctor and ask them to check your serum levels of 25-hydroxyvitamin D.
Vitamin D supplements have the potential to interact with several common medications and certain medications may impact your body’s Vitamin D status. Ask your doctor about the potential for these interactions.
Dietary Supplement Fact Sheet: Vitamin D. http://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional
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